1. Field of the Invention
This invention relates to a system for processing a photographic image, and particularly to an image processing method and apparatus for automatically adjusting the density information of pixels contained in an image data set.
2. Discussion of the Related Art
Conventionally, a photograph is provided by printing an image onto photographic paper where the image has been shot on a film using a camera. The film (specifically, a negative film) has exposure characteristics and these characteristics have some margin or variations considering the varied conditions at the time of shooting. However, the photographic paper on which the image will be printed does not have such exposure characteristics. Accordingly, an image appearing in the film may not appear exactly on the printing paper.
For example, in case of photographing a person""s figure where the background contains a window into which bright sunlight shines, it is difficult to print both the person""s figure and the background with appropriate densities. This is because if it is desired to print the person""s figure on the photographic paper using an appropriate density, the background is likely to be whited out due to under exposure. Alternatively if it is desired to print the background on the photographic paper with an appropriate density, the figure is likely to be blacked out due to over exposure.
Previously, an operation called xe2x80x9cmasked printingxe2x80x9d has been necessary for printing both the person""s figure and the background onto the photographic paper when the film is shot using the conditions described above. This operation requires a high level of printing skill since it varies the light exposure of one part of the photographic paper from another part by exposing one part of the photographic paper while masking the other part. Accordingly, masked printing has a problem in that it should be done by a manual operation using experts and thus it is expensive.
Also, there is a problem that, if a film is photographed in conditions where it is under exposed or over exposed, it is necessary to appropriately adjust the duration for printing the photographed image on the film to obtain a good photograph print.
It is an object of the present invention to provide an image processing method and an image processing apparatus that makes the masked printing technique unnecessary by automatically adjusting the density information of the pixels containing the image data.
Further, it is another object of the present invention to provide an image processing method and apparatus that makes it unnecessary to adjust the duration for printing an image even when the image or part of the image is photographed with conditions where it is under exposed or over exposed.
An image processing method of the present invention comprises the steps of dividing the image data into a plurality of regions based on color information of pixels contained in the image data; and adjusting the density information of the pixels contained in at least one particular region among the plurality of regions, whereby the above objects are achieved.
Another image processing method of the present invention is an image processing method for processing image data containing a plurality of pixels and comprises the steps of mapping the plurality of pixels into a plurality of points in color space, based on color information for each of the pixels; detecting a plurality of spaces contained in the color space, in accordance with the concentration of the plurality of points in the color space; adjusting the average density information of at least one particular space among the plurality of spaces; and adjusting density information of pixels contained in the particular space, based on the average density information of the particular space, whereby the above objects are achieved.
The step of adjusting the density information of the pixels may further comprise the step of adjusting the density information of pixels contained in a portion of the image data corresponding to an over exposed portion or an under exposed portion of a film.
An image processing apparatus of the present invention comprises means for dividing image data into a plurality of regions based on color information of pixels contained in the image data; and means for adjusting the density information of the pixels contained in at least one particular region among the plurality of regions, whereby the above objects are achieved.
Another image processing apparatus of the present invention is an image processing apparatus for processing image data containing a plurality of pixels and comprises means for mapping the plurality of pixels into a plurality of points in color space, based on the color information for each of the pixels; means for detecting a plurality of spaces contained in the color space, in accordance with the concentration of the plurality of points in the color space; means for adjusting the average density information of at least one particular space among the plurality of spaces; and means for adjusting density information of pixels contained in the particular space, based on the average density information of the particular space, whereby the above objects are achieved.
The means for adjusting the density information of the pixels may further comprise means for adjusting the density information of pixels contained in a portion of the image data corresponding to an over exposed portion or an under exposed portion of a film.
According to the present invention, based on the color information of pixels contained in the image data, the density information of the pixel is automatically adjusted. The masked printing technique previously used by experts thus becomes unnecessary.
According to further aspects of the present invention, the density information of the pixels contained in the portion of the image data corresponding to the under exposed or over exposed portion of the film is automatically adjusted. Thereby, even if the film is photographed with under exposed or over exposed conditions, it becomes unnecessary to adjust the time duration for printing the photographed image onto the photographic paper.